EFFECT OF COCULTURE ON SUBSEQUENT SURVIVAL AND IMPLANTATION OF CRYOPRESERVED HUMAN EMBRYOS

Purpose: This retrospective analysis was designed to assess the perfor mance of human embryos following cryopreservation based on whether the y were originally developed in standard culture medium (65 cycles, 223 embryos) or cocultured on partial monolayers of bovine oviductal epit helial cells (63 cycles, 198 embryos). Embryo cryosurvival and implant ation were compared between the study group and the contemporaneously matched controls. Results: During a 2-year period when no factors of t he cryopreservation program were altered, 63 transfers of 159 survivin g thawed control cleavage-stage embryos (71.3% survival) that were 54% intact gave rise to 11 viable pregnancies (17.5%/ET), to yield an imp lantation rate of 6.9% per embryo. Sixty-three transfers of 147 thawed cocultured embryos (74.2% survival) that were 61% intact gave rise to 17 viable pregnancies (27%/ET), which gave an implantation rate of 13 .6% per embryo that was significantly higher than the control group (P < 0.05). Conclusion: Coculture of embryos prior to cryopreservation d oes nor appear to improve cryosurvival; however, it does improve impla ntation postthaw compared with embryos following standard culture prio r to cryopreservation.